1. Field of the Invention
The present invention generally relates to a high voltage semiconductor device, and more particularly to a high voltage semiconductor device having a high breakdown voltage and a fabrication method thereof.
2. Description of the Related Art
Generally, a high voltage transistor has a property of driving a signal processing part which processes an electrical signal and a mechanical part which operates according to a processing result of the electrical signal, the property being different from most semiconductor devices. In order to effectively drive the mechanical part, high power (current.times.voltage) should be provided. In most cases, a large current is provided in the application of high power. There exist, however, many cases needing a high voltage difference. In such cases, when the driving voltage approaches 100V, a high breakdown voltage should be ensured in order to protect the high voltage semiconductor device. A conventional high voltage semiconductor device essentially requires an optimized drain structure. In a conventional case, a potential absorption method using a doping profile is used. In further detail, resistance difference due to a concentration difference between n.sup.+ /n.sup.- doped regions, and dispersion of electric field are used. As a result, the area of drain region increases with the increase in the driving voltage. Therefore, when current above a certain level, is abruptly introduced to a drain region having a resistance which allows only a current below the certain level to flow. As a result, there is an increased probability of breakdown due to joule heat, of snapback breakdown due to hot carriers.